Share immune system Post the Definition of immune system to Facebook Share the Definition of immune system on Twitter. Time Traveler for immune system The first known use of immune system was circa See more words from the same year.
Style: MLA. English Language Learners Definition of immune system. Kids Definition of immune system. Medical Definition of immune system. Get Word of the Day daily email! Test Your Vocabulary. Can you spell these 10 commonly misspelled words? White blood cells are the key players in your immune system. They are made in your bone marrow and are part of the lymphatic system. White blood cells move through blood and tissue throughout your body, looking for foreign invaders microbes such as bacteria, viruses, parasites and fungi.
When they find them, they launch an immune attack. White blood cells include lymphocytes such as B-cells, T-cells and natural killer cells , and many other types of immune cells. Antibodies help the body to fight microbes or the toxins poisons they produce. They do this by recognising substances called antigens on the surface of the microbe, or in the chemicals they produce, which mark the microbe or toxin as being foreign. The antibodies then mark these antigens for destruction.
There are many cells, proteins and chemicals involved in this attack. The complement system is made up of proteins whose actions complement the work done by antibodies. The lymphatic system is a network of delicate tubes throughout the body. The main roles of the lymphatic system are to:. The spleen is a blood-filtering organ that removes microbes and destroys old or damaged red blood cells. It also makes disease-fighting components of the immune system including antibodies and lymphocytes.
Bone marrow is the spongy tissue found inside your bones. It produces the red blood cells our bodies need to carry oxygen, the white blood cells we use to fight infection, and the platelets we need to help our blood clot.
The thymus filters and monitors your blood content. It produces the white blood cells called T-lymphocytes. As well as the immune system, the body has several other ways to defend itself against microbes, including:.
A rise in body temperature, or fever , can happen with some infections. This is actually an immune system response. A rise in temperature can kill some microbes. Fever also triggers the body's repair process. It is common for people to have an over- or underactive immune system. Overactivity of the immune system can take many forms, including:. Underactivity of the immune system, also called immunodeficiency , can:. An underactive immune system does not function correctly and makes people vulnerable to infections.
It can be life threatening in severe cases. Your body also makes other cells to fight the antigen. Afterwards, your immune system remembers the antigen. If it sees the antigen again, it can recognize it. It will quickly send out the right antibodies, so in most cases, you don't get sick. This protection against a certain disease is called immunity. Sometimes a person may have an immune response even though there is no real threat.
This can lead to problems such as allergies , asthma , and autoimmune diseases. If you have an autoimmune disease, your immune system attacks healthy cells in your body by mistake. Other immune system problems happen when your immune system does not work correctly. These problems include immunodeficiency diseases. If you have an immunodeficiency disease, you get sick more often. Your infections may last longer and can be more serious and harder to treat.
They are often genetic disorders. There are other diseases that can affect your immune system. For example, HIV is a virus that harms your immune system by destroying your white blood cells. People with AIDS have badly damaged immune systems. They get an increasing number of severe illnesses.
The information on this site should not be used as a substitute for professional medical care or advice. That means that an antibiotic that works for a skin infection may not work to cure diarrhea caused by bacteria.
Using antibiotics for viral infections or using the wrong antibiotic to treat a bacterial infection can help bacteria become resistant to the antibiotic so it won't work as well in the future.
It is important that antibiotics are taken as prescribed and for the right amount of time. If antibiotics are stopped early, the bacteria may develop a resistance to the antibiotics and the infection may come back again.
Note: Most colds and acute bronchitis infections will not respond to antibiotics. Health Home Conditions and Diseases. There are two main parts of the immune system: The innate immune system, which you are born with. These two immune systems work together. The innate immune system This is your child's rapid response system. The acquired immune system The acquired immune system, with help from the innate system, produces cells antibodies to protect your body from a specific invader.
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